Hosted and produced by Lazlow (who also co-wrote the script along with Dan Houser), is the only radio station in the game that does not feature music. Much like the talk radio stations in the real world, Chatterbox features a format in which listeners call in with opinions, concerns, and complaints, and the host responds with their take on the situation. The station also features two long interviews with fictional Liberty City characters — the pacifist, organic food-eating martial artist "Reed Tucker", and the "cheap pimp from upstate", Fernando Martinez (a future recurring character in the GTA series, with a lot of experience in and out of radio). Chatterbox FM is the Triad's favorite radio station.
This being Grand Theft Auto, the callers and calls are naturally humorous, and include such jokes as a man calling to tell Lazlow that he needs a nanny to spank him (a call so popular it would spawn a version about witches in Vice City and even its own commercial in San Andreas), a man calling in regard to taxes (which he pronounces like "Texas"), Toni Cipriani calling with an embarrassing story about his mother, a man who hates clothes ("Does a lion wear clothes? And the lion is the king of the jungle!"), and Maria Latore/LaTorra calling regarding relationship troubles with her boyfriend, the unnamed main character (in GTA:SA he is referred to as "Claude" and is also mute) Maria on Claude: "He don't talk much".
One caller calls in to talk about turnips. Lazlow tells this caller that "This isn't 'Gardening with Maurice'." ("Gardening with Maurice" would later be featured on WCTR, a talk radio station in San Andreas.)
One of the calls is from a SPANK-head, referring to the increasingly popular leisure drug prevalent in the game. He refers to Lazlow as a pansy and goes on about conspiracies and government brainwashing involving toothpaste.
A caller who indicates he is fond of eating animals of any kind says he sometimes finds pigeons that have notes attached, commenting "it's like a fortune cookie with wings". Another caller, a woman from "Citizens Raging Against Phones" (C.R.A.P.), a fictional pressure group with GTA3 against the use of telephones, declares that the group uses carrier pigeons in the place of telephones, but that they keep going missing, implying that the first caller is, in fact, eating these pigeons. In Grand Theft Auto: Liberty City Stories, the predecessor to C.R.A.P. was Citizens United Negating Technology, and its caller to Chatterbox warns that they will first shut off "the internet, then we're going after the phones."
Reed Tucker is a guest on Chatterbox. It is said by both Lazlow and Reed that he has a food market ("Now and Zen") in Trenton, but none exists in the game. After the Reed Tucker conversation a caller yells at the end of the call "free Kevin!", reference to infamous computer hacker Kevin Mitnick. Reed also calls into the radio in San Andreas, making a comment about masticating that the show's host interprets as masturbation due to Reed's lisp.
The replies Lazlow gives to his callers are usually comically caustic and opinionated. A common reply to nonsense callers is "Well I'm sure that's a lesson to us all." An interesting point is that in this game, Lazlow off-handedly mentions that he is only hosting Chatterbox because he "got kicked off the rock station", and this is proved to be entirely true in the next game in the series, Grand Theft Auto: Vice City as he is the host of the radio station "V-Rock". He is also heard on Grand Theft Auto San Andreas on WCTR later on as well as being the intern to Couzin Ed on V-Rock in the Vice City prequel Grand Theft Auto: Vice City Stories. When he first takes the Chatterbox job in 1998, he is referred to as the host "run out of both Vice City and San Andreas."
The many guests on the station were voiced by: Lucien Jones, Karin Bykowski, Hank Stewart, Abbi Davis, Mellowvision.com, Paul Maloney, bernieS, Frank Fava, Kit Halsted, Joe Casalino, Dan Houser, Jay Crutcher, Frank Chavez, DJ Rush, A.M. Watson, Laura Bykowski, Navid Khonsari, Sherry Wohglmuth, Porkchop, Renaud Sebbane, Kyle Maclachlan, Sabby, Kim Schaefer, Debi Mazar, Nick Mandelos, David Connell, Reed Tucker, Jennifer Kolbe, Ami Plasse, Keith Broadus, Cameo Carlson, JD Leeds and Michael Madsen
In Grand Theft Auto: Liberty City Stories, which is set three years before GTA III, Lazlow's callers are diverse but generally offensive, including an Internet freak who wants to knock down the Liberty City cathedral, a gothic girl wanting to cast spells on Lazlow, a foul-mouthed cannibal who asks why he can't eat people, Ben Sparks, a man obsessed with shaving and a 7-year-old girl who knows an awful lot of swearwords for someone so young. A guy complaining about Vinewood saying that "if I see one more damn movie with ten kids, a dog in a wheelchair and some damn baseball championship. I'm going to start killing people and blame it on Vinewood" Gregg Hughes. The mother of the game's main character (Ma Cipriani) also calls in, but gets angry with Lazlow, calling him Lazarus, and threatening him with a Mafia assassination. This is a homage to Grand Theft Auto III when Toni calls Lazlow explaining how much his mother controls his life.